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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 09:22:09 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 09:22:09 +0000
commit43a97878ce14b72f0981164f87f2e35e14151312 (patch)
tree620249daf56c0258faa40cbdcf9cfba06de2a846 /third_party/rust/tokio/src/io/util/take.rs
parentInitial commit. (diff)
downloadfirefox-upstream.tar.xz
firefox-upstream.zip
Adding upstream version 110.0.1.upstream/110.0.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/tokio/src/io/util/take.rs')
-rw-r--r--third_party/rust/tokio/src/io/util/take.rs137
1 files changed, 137 insertions, 0 deletions
diff --git a/third_party/rust/tokio/src/io/util/take.rs b/third_party/rust/tokio/src/io/util/take.rs
new file mode 100644
index 0000000000..df2f61b9e6
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+++ b/third_party/rust/tokio/src/io/util/take.rs
@@ -0,0 +1,137 @@
+use crate::io::{AsyncBufRead, AsyncRead, ReadBuf};
+
+use pin_project_lite::pin_project;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use std::{cmp, io};
+
+pin_project! {
+ /// Stream for the [`take`](super::AsyncReadExt::take) method.
+ #[derive(Debug)]
+ #[must_use = "streams do nothing unless you `.await` or poll them"]
+ #[cfg_attr(docsrs, doc(cfg(feature = "io-util")))]
+ pub struct Take<R> {
+ #[pin]
+ inner: R,
+ // Add '_' to avoid conflicts with `limit` method.
+ limit_: u64,
+ }
+}
+
+pub(super) fn take<R: AsyncRead>(inner: R, limit: u64) -> Take<R> {
+ Take {
+ inner,
+ limit_: limit,
+ }
+}
+
+impl<R: AsyncRead> Take<R> {
+ /// Returns the remaining number of bytes that can be
+ /// read before this instance will return EOF.
+ ///
+ /// # Note
+ ///
+ /// This instance may reach `EOF` after reading fewer bytes than indicated by
+ /// this method if the underlying [`AsyncRead`] instance reaches EOF.
+ pub fn limit(&self) -> u64 {
+ self.limit_
+ }
+
+ /// Sets the number of bytes that can be read before this instance will
+ /// return EOF. This is the same as constructing a new `Take` instance, so
+ /// the amount of bytes read and the previous limit value don't matter when
+ /// calling this method.
+ pub fn set_limit(&mut self, limit: u64) {
+ self.limit_ = limit
+ }
+
+ /// Gets a reference to the underlying reader.
+ pub fn get_ref(&self) -> &R {
+ &self.inner
+ }
+
+ /// Gets a mutable reference to the underlying reader.
+ ///
+ /// Care should be taken to avoid modifying the internal I/O state of the
+ /// underlying reader as doing so may corrupt the internal limit of this
+ /// `Take`.
+ pub fn get_mut(&mut self) -> &mut R {
+ &mut self.inner
+ }
+
+ /// Gets a pinned mutable reference to the underlying reader.
+ ///
+ /// Care should be taken to avoid modifying the internal I/O state of the
+ /// underlying reader as doing so may corrupt the internal limit of this
+ /// `Take`.
+ pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut R> {
+ self.project().inner
+ }
+
+ /// Consumes the `Take`, returning the wrapped reader.
+ pub fn into_inner(self) -> R {
+ self.inner
+ }
+}
+
+impl<R: AsyncRead> AsyncRead for Take<R> {
+ fn poll_read(
+ self: Pin<&mut Self>,
+ cx: &mut Context<'_>,
+ buf: &mut ReadBuf<'_>,
+ ) -> Poll<Result<(), io::Error>> {
+ if self.limit_ == 0 {
+ return Poll::Ready(Ok(()));
+ }
+
+ let me = self.project();
+ let mut b = buf.take(*me.limit_ as usize);
+
+ let buf_ptr = b.filled().as_ptr();
+ ready!(me.inner.poll_read(cx, &mut b))?;
+ assert_eq!(b.filled().as_ptr(), buf_ptr);
+
+ let n = b.filled().len();
+
+ // We need to update the original ReadBuf
+ unsafe {
+ buf.assume_init(n);
+ }
+ buf.advance(n);
+ *me.limit_ -= n as u64;
+ Poll::Ready(Ok(()))
+ }
+}
+
+impl<R: AsyncBufRead> AsyncBufRead for Take<R> {
+ fn poll_fill_buf(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<&[u8]>> {
+ let me = self.project();
+
+ // Don't call into inner reader at all at EOF because it may still block
+ if *me.limit_ == 0 {
+ return Poll::Ready(Ok(&[]));
+ }
+
+ let buf = ready!(me.inner.poll_fill_buf(cx)?);
+ let cap = cmp::min(buf.len() as u64, *me.limit_) as usize;
+ Poll::Ready(Ok(&buf[..cap]))
+ }
+
+ fn consume(self: Pin<&mut Self>, amt: usize) {
+ let me = self.project();
+ // Don't let callers reset the limit by passing an overlarge value
+ let amt = cmp::min(amt as u64, *me.limit_) as usize;
+ *me.limit_ -= amt as u64;
+ me.inner.consume(amt);
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn assert_unpin() {
+ crate::is_unpin::<Take<()>>();
+ }
+}